The present application claims priority to Japanese Application No. P11-179290 filed Jun. 25,1999 which application is incorporated herein by reference to the extent permitted by law.
1. Field of the Invention
This invention relates to a carbonaceous complex structure employing a fullerene based thin film, and a manufacturing method therefor.
2. Description of Prior Art
Recently, a sensor device, comprising a carbonaceous thin film and a thin film of a heterogeneous material from it, both layered on a substrate, has been developed in order to exploit characteristics proper to the carbonaceous thin film, such as electric conductivity.
It is an object of the present invention to provide a carbonaceous complex material comprising the above-described carbonaceous thin film in combination with a fullerene thin film for improving adhesion between neighboring layers and for realizing peculiar optical properties, such as charge separation capability.
In one aspect, the present invention provides a carbonaceous complex structure comprising a layered set of a substrate, a carbonaceous thin film and a fullerene thin film.
In another aspect, the present invention provides a method for manufacturing a carbonaceous complex structure including a step of forming a carbonaceous thin film on a substrate by pyrolysis of an organic compound and a step of forming a fullerene thin film.
In the carbonaceous complex structure of the present invention, since the carbonaceous thin film and the fullerene thin film (fullerene vapor-deposited film or fullerene polymer film as explained later in detail), layered on substrate, are both formed of carbon, and are superior in affinity to each other, adhesion between the two films demonstrate is strong. The smoother the substrate surface, the more strongly the carbonaceous thin film can be affixed to the substrate, thus providing a dense film exhibiting high mechanical strength. Therefore, the carbonaceous thin film can be bonded strongly to the fullerene thin film layered thereon.
On the other hand, in the carbonaceous complex structure of the present invention, the carbonaceous thin film exhibits superior electrical conductivity on the order of 10-2 S/cm. If a fullerene thin film is deposited thereon, this fullerene thin film has valence band edge lower by approximately 2.0 eV than that of the valence band edge of the carbonaceous thin film and is able to operate as a donor/acceptor to permit charge separation by photo absorption. So, the carbonaceous complex structure finds application as a solar cell. Moreover, since the carbonaceous complex structure has its electrical conductivity changed clearly with respect to a substrate, it finds latent usage as a sensor device having superior durability with respect to the gas or the pressure.
The carbonaceous complex structure, having this superior effect, may be produced by the above-defined method according to the present invention.
The manufacturing method according to the present invention, including a step of forming a carbonaceous thin film and a fullerene thin film on a substrate, can be carried out easily because of a smaller number of steps to produce the carbonaceous complex structure efficiently.
Specifically, with the carbonaceous complex structure of the present invention, the carbonaceous thin film and the fullerene thin film, both layered on a substrate, are both formed of carbon and hence exhibit high affinity so that the two films exhibit high adhesion to each other.
Moreover, the smoother the substrate surface, the more strongly can the carbonaceous thin film be bonded thereto to form a dense film of high mechanical strength. In addition, the carbonaceous thin film surface can be a smooth surface to profile the substrate surface, while it can be bonded strongly to the fullerene thin film deposited thereon.
With the carbonaceous complex structure of the present invention, having the above-mentioned layered structure, permits charge separation by photo absorption and is able to form a so-called donor-acceptor heterojunction. Moreover, it has its electrical conductivity definitely changed with respect to the substrate and hence finds application as a solar cell or sensor of high durability.